Tag Archives: ubuntu

Restarting the Linux sound subsystem

Sometimes my laptop gets to a state in which sound works through the built-in speakers, but not through the headphone jack. Possibly my solution is too brutal, but it works -  restarting the whole sound subsystem. I guess that it may come handy in other situation: the ability to restart a subsystem instead of rebooting the machine, is always an advantage.

The rationale is simply reloading the kernel module that acts as a driver to our sound hardware. Reloading isn't easy, as:

  1. Kernel modules use this module.
  2. User processes use this module.

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Reviving the hibernate feature on Debuntu

My laptop's battery had just died. It made me realize how much I depend on it, for changing my working location, either when computer is awake or asleep for many hours. Without a battery, the sleep (aka suspend-to-ram) feature is less useful, for the tiniest power interruption would kill it. Continue reading

The mysterious case of broken SSH client (“connection reset by peer”)

Update: from the info I've gathered, this is most probably a problem with some Cisco IDS/DPI is running on the ethernet equipment. Workaround is available in the content below, I still don't know what's the real solution here (Cisco equipment config? update Cisco firmware?)

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Starting with 5.7p1, ssh client on specific environments fails connecting to specific (usually old versioned) servers. I reproduced it on a particular network, while trying to connect using new ssh client (5.8p1, Ubuntu 11.04) to an old server (default SSH server on RedHat 5.4).

Motivation

This issue is around for quite a while, but is very tricky to reproduce or understand. What bothered me most is that many people reported it to different forums, each posting only a few (different) pieces of the puzzle. So my motivation here is to try and summarize the relevant info from multiple places. I'll do my best to update this post when I hear something new.

Complete Fact list Continue reading

Make DHCP auto-update the DNS

Update: added a new post on configuring Solaris, link below.

Motivation

In today's dynamic R&D network environments, it's not easy to keep the DNS records up-to-date: hosts are reinstalled/renamed/added frequently, virtual machines are so easy to deploy and destroy, DHCP allocates different IPs..

This even leads to pitiful situations, in which people get used to referring to computer by their IPs (or using /etc/hosts), because the DNS cannot be trusted to reflect the reality.

Solution

DHCP servers have the ability to send dynamic DNS updates, as they allocate IPs to clients. The great thing, is that it even works out-of-the-box on some operating systems. Still, if it doesn't, here are 3 things to care about, so to enable this feature: Continue reading

Booting Linux from iSCSI

What is this long post about?

iSCSI is standard for accessing block devices (e.g. disks) over network, just as if they were local SCSI devices. That's similar to AoE and FCoE, although the latter two are good for the LAN only, while iSCSI is over IP thus is good on WAN. This article would focus iSCSI but could be used as a base for doing similar things with AoE and FCoE.

So, iSCSI in the simplest configuration, allows us to mount and manage a data disk that is physically connected to a remote computer (the "server", aka target) from our own computer (client, aka initiator) .

On this post I'll discuss the deep details of the more advanced stage: having the root (also boot) disk on a remote computer, so client could remotely boot from it. Surprisingly it can be done even with relatively old hardware.

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Long live Debian!

After the Lenny release, nobody can say that Lenny is not a rock-solid OS. Furthermore, nobody can say that sid(unstable) is not bleeding edge enough. Especially after kde4.2 made it into sid. The kde4.2 upgrade process succeeded smoothly on my place. I've also "upgraded" my Lenovo X61 laptop from Ubuntu to Debian sid with a surprising success. I really feel better now, with Debian.

Still, when trying to convince people why Debian is superior than Ubuntu, it's hard to find the rational reasons. After all, Ubuntu is a Debian with more money and a larger community. After some thought, I've caught two possible reasons:

  1. Expert community: the average debian bug report is much more professional than an ubuntu bug, which is sometimes just a mess made of dozens of people saying "ohh it also happens to me!! please fixxx!". In other words, Debian users seem to be more tech savvis.
  2. KDE is quite a stranger in ubuntu. Kubuntu is quite uncommon, which makes it a little less intensively developed. In Debian there's no such partition. Debian is KDE as much as it's GNOME. I like KDE, so it feels more native to use Debian.

What do you think, why is Debian superior in your opinion? (or is it not..)